//写入cookie
function SetCookie(name,value)
{
	var Days = 30; //此 cookie 将被保存 30 天
	var exp = new Date();
	exp.setTime(exp.getTime() + Days*24*60*60*1000);
	document.cookie = name + "="+ escape (value) + ";expires=" + exp.toGMTString()+ ";path=/";
}
///删除cookie
function delCookie(name)
{
	var exp = new Date(); 
	 exp.setTime(exp.getTime() - 1); 
	 var cval=getCookie(name); 
	 if(cval!=null) 
	     document.cookie= name + "="+cval+";expires="+exp.toGMTString()+ ";path=/"; 
}



//读取cookie
function getCookie(name)
{
	var arr = document.cookie.match(new RegExp("(^| )"+name+"=([^;]*)(;|$)"));
	if(arr != null)
		return unescape(arr[2]);
	return null;
}